Engineering 3D Human Cardiac Ventricular Models with Controllable Architecture

Abstract

Tissue engineering combined with the power of stem cell technology provides unprecedented opportunity to interrogate and discover human biology. The derivation of human cardiomyocytes from induced pluripotent stem cells (iPSCs) has enabled the development of de novo cardiac tissues that recapitulate several characteristics of functional human myocardium. These platforms act as advanced models with which cardiac development, biomechanics, and disease pathology can be reverse engineered to glean otherwise unobtainable information that has great significance to human health. Despite this progress, tissue engineering is in its infancy, and the ability to produce cardiac tissues that mimic the function of mature adult myocardium has proven to be quite challenging. Using immature tissues for disease modeling or developing novel therapeutics poses a potential danger for generating falsely positive or negative results. To combat this risk, there has been significant effort in developing biofabrication strategies to recapitulate the complex tissue architecture of the myocardium. However, there are few platforms available that can recreate the multiscale organization of the heart, including tissue anisotropy, helical myocardial organization, and ventricular and atrial chamber geometries. To address this shortcoming, we have developed a nanopatterned cell sheet technology for fabrication of complex 3D cardiac ventricular models with controllable cellular architecture. In this approach flexible thermoresponsive nanofabricated substrates (fTNFS) were used to create sheets of organized cardiac tissue and cast them into simplified chamber geometries such as a hollow tube or cone shape. These tissues exhibited spontaneous beating and could create measurable pumping pressures. Additionally, we measured functional benefits from tissues with anisotropic cellular patterning as compared to tissues with non-biomimetic cellular arrangements. We also observed that tissues patterned with circumferential cellular alignment exhibited surprising cellular remodeling where the cells rotated almost 90 degrees in orientation from their initial circumferential pattern. Upon modeling this effect computationally using finite element analysis, we discovered large gradients of shear stress perpendicular to cellular alignment that may have motivated cellular reorganization. Together, these findings demonstrate the importance of mimicking myocardial architecture in engineered tissue models. These works provide an advanced platform for studying tissue structure-function relationships in cardiac development and disease.